The secretory response in dissociated acini from the rat submandibular gland

Rat submandibular gland was dissociated by enzymatic digestion with collagenase and hyaluronidase, followed by mild mechanical shearing and filtration through a nylon mesh. The dissociated cell populations contained predominantly groups of acinar cells which maintained their acinar arrangement. The morphological and functional viability of the cells was confirmed by electron microscopic examination and a normal secretory response to beta-adrenergic or cholinergic stimulation was observed. Both isoproterenol (IPR) and carbachol caused the fusion of secretory granules into large vacuoles which were also continuous with the lumen, and into which the secretory product was released. Secretion was assessed quantitatively from the incorporation of 14C-glucosamine into the acinar cells and its subsequent release into the culture medium as labelled glycoprotein. IPR stimulated secretion to 125% of untreated controls in the concentration range t x 10(-5) to 5x 10(-7) M and to 110% of controls at 5 x 10(-8) M, after 40 min incubation. Carbachol stimulated secretion to 131% of controls at 5 x 10(-5) M and to 115% at 5 x 10(-6) M but had no effect at 5 x 10(-7) or 5 x 10(-8) M. The secretory response was blocked by the respective beta-adrenergic and cholinergic antagonists, propranolol and atropine. These findings show that dissociated rat submandibular acinar cells provide a useful in vitro model for the study of mucus synthesis and secretion.